Rotary bit



lNVENTO c. A'. DEAN v ROTARY BIT Nov. 28, 1939.

' Original Filed Aprii 17, 1937 .Y 5 V m z m M r a m m Patented Nov 28,1939 PATENT OFFICE amass ao'ranr BIT Charles A. Dean, Compton, cam.

Substitute for abandoned application Serial No. 137,404, April. 17,1937. This application December 1, 1938, Serial No. 243,401

4 Claims. (Cl 255-71) This invention pertains to improvements inearth-drilling bits, and particularly to means for mounting a rotatablecutter in a.rotary bit.

This application is a substitute for my earlier filed application S. N.137,404, filed April 17,

-l937, and which became abandoned on April 6,

. An object of this invention is to provide a cutter assembly that issturdy, and also one that is.

adapted to minimize wear and looseness. of a cutter in its, support. ;'Afurther object is to provide a simple assembly'and in large measure toutilize replaceable parts. in the parts and combination and arrangementthereof illustrated in the accompanying description and drawing andparticularly pointed out in the appended claims.

In the drawing, the figure shows a bit head partly in elevation andpartly in vertical section through a roller cutter and mountingtherefor,

according to a preferred embodiment of this invention.

According 'to the present invention a rotatable cutter is provided witha projecting hub portion for support upon a trunnion bearing. Moreparticularly the projecting hub is arranged within a wear washersupported in the bit head to absorb both. upward and side thrusts inuse. In a specific embodiment of this invention, as at presentpreferred, a roller cutter is formed with a projecting hub directedinwardly toward the center of the bit head, and is mounted on'trunnionsbetween supporting legs of the bit head with a flange of wear-resistantmaterial around the hub portion of the cutter. As such wear-resistantmaterial, "stellite" or other. well-known substances are suitable.

Referring more particularly to the drawing, there is shown a rotarybit-head I with roller cutters 2, 3 mounted between .opposite pairs oflegs or support arms 4, 5 and 6, 1 formed at thebottom ofjthe bit head.Between these outer cutters are inner cutters illustrated by 8 in thedrawing.

' A portion of the bit head is cut away near cutter 3 to illustrate themounting of the outer cutters.

Cutter 3 is shown with an elongate hub portion 9'supported upon atrunnion bolt III, which is secured to the bit head. Hub portion 9 isadapted to space the cutter 3 away from the bit head leg adiacenttothehub sufliciently for a wearresistant flange I I to be secured' in thespace thus provided. In the specific form shown .in the drawing hub'9projects from cutter 3 toward the inner leg 6 of the bit head so thatannular washer The invention consists plug I3 is further secured, as byweld IE, to leg I of the bit head. I

II of wear resistantmaterial may be inserted between cutter 3 and leg 6and preferably to bear against leg 6 and the fronting face of cutter 3.

A further preferred feature of this invention re-' sides in providing aportion of leg 6concentric 5 with hub 9 so as to receive ring I2 of wearresistant material as a sleeve axially of the cutter hub.

As shown in the drawing this may be'accomplished by recessing leg 6 ofthe bit head sufil ciently to receive ring I2. As shown, ring I2 and 10washer I I may be unitary with each other; this in the claims isdesignated'as a flange. By' such means extensive bearing andwear-resistant surface is provided for the cutter. Moreover a snug fitand extensive surface of wear resistant ma- 15 terial II, I2 along thehub 9 and adjacent face 'of the cutter assure. continued alignment andminimum whipping or play of the'cutter in use.

The advantages of this cutter mounting are enhanced by combining theabove-described features of this invention with additional improvements.Thus trunnion bolt III is fitted through ,hub 9 and is supported bybifurcated legs 6 and 1 of the bit head. Bolt I0 is threaded to tightencuter 3 against wear rings I I, I2. Further security is provided byflanged plug I3 inserted within a base in outer leg 1 of the bit headand threaded internally to receive bolt Ill. Thus plug I3 wear washerII, I2 and bearings I4, so that the bearings I4 are relieved ofexcessive pressure. Plug I3 in one form of this invention is split topermit insertion to form; the ball racewhen the cutter assembly iscomplete andtrunnion bolt I0 drawn tight, the outer face of trunnion Itwill be evident that on advantage of this invention resides in provisionto pre-assemble a cutter-ready for quick replacement in a bit head inthe field when necessary. A further advantage of considerable-importanceresides in the ability of wear washer II, I2 and hub 9 to receive bothupward and side thrust in use, particularly on an extensive innersurface of the cutter as shown, to distribute stressover an extensivesurface and to maintain alignment of the cutter despite extensive use. I

While in accordance with the patent statutes a particular embodiment ofthis invention has been described, and the best mode of application nowcontemplated, for illustration of the principles thereof, it is evidentthat variations and other specific arrangements arecontemplated andvarious adaptations of this invention may now be made by those skilledin the art, "within the scope of the appended claims.

I claim:

1. In combination in an earth drill, a bit head comprising a pair ofbifurcated support arms, a

roller cutter with a bearing hub projecting from one face thereof, awear-resistant element mounted as a sleeve about the hub to bear againstthe adjacent support arm, a trunnion bolt in one arm supporting the hub,and in the other arm a trunnion plug supporting the roller cutter andmovably engaged by the trunnion bolt to bedrawn against the rollercutter.

2. In combination in an earth drill, a bit head comprising a pair ofsupport arms, a roller cutter with a bearing hub projecting from oneface thereof, a wear resistant flange mounted around the hub against theadjacent face of the cutter, a rotatable low friction element mounted tobear against the opposite face of the cutter, a trunnion bolt extendingthrough the hub to one of the adjacent support arms, a trunnion plug inthe opposite support arm formed to retain the rotatable low frictionelement and threadedly connected to the trunnion bolt to be drawnthereby against the face of the roller cutter.

3. In combination in an earth drill, a bit head comprising a pair ofsupport arms, a roller cutter with a bearing hub projecting downwardlytoward the center of the drill from the inner face of the cutter, a wearresistant washer mounted around the hub against the adjacent inner faceof the cutter, a trunnion bolt extending through the hub to the innersupport arm, a recessed portion in the outer face of the cutterand arotat able low friction element mounted in the recess for supportagainst the arm adjacent thereto, a trunnion plug in the recess andextending into the outer support arm and threadedly connected to thetrunnion bolt to be drawn thereby against the face of the roller cutter.

4. An earthYirili comprising in combination a bit head having securedthereto a supporting arm for a roller cutter, a roller cutter mountedthereon having a hub projecting toward the supporting arm and having aface adjacent the hub generally fronting the supporting arm, and anannular member of wear-resisting material fitted externally of the huband against the adjacent face and the supporting arm, the supporting armcontaining a recess to receive the hub and annular wear-resistingmember.

CHARLES A. DEAN.

